This invention relates to joystick controls in general and in particular to joystick controls which generate a digital signal indicative of the relative position of the joystick.
Joystick controls are well known in the prior art. Such controls are often utilized to position or locate a cursor or other indicator at a particular location in a video display such as those displays utilized in video arcade games. Many prior art joysticks are analog devices and utilize one or more potentiometers to provide an analog indication of the relative position of the joystick. This is typically accomplished by mounting the potentiometers in fixed relationships to the joystick and then controlling one potentiometer by movement of the joystick in an X plane and controlling a second potentiometer by movement of the joystick in the Y plane. Thus, the position of the joystick determines the relative resistance of two potentiometers which in turn are utilized to alter suitable electrical signals. Since many such systems utilize microprocessor control systems which require digital inputs, it is common to couple the outputs of such analog joystick controls through an analog to digital converter prior to coupling these signals to the microprocessor.
Recently, several designs have been utilized to directly generate digital signals which are indicative of the relative position of the joystick. These so-called digital joysticks are often complex devices which utilize a plurality of complex electrical contactors to generate a digital signal indicative of the position of the joystick. Examples of such digital joysticks can be seen in U.S. Pat. No. 4,148,014 and U.S. Pat. No. 4,161,726.
As those skilled in the art will appreciate, there are numerous advantages to be obtained with a joystick control system which generates digital signals indicative of the joystick position; however, the increased complexity of these systems often makes manufacture and assembly very difficult. This is particularly true in those systems in which it is desired to bias the joystick to a neutral or centered position so that in the absence of a continual manual input the movement of the controlled cursor will stop rather than continue in the direction last entered.